U.S. patent application number 12/989589 was filed with the patent office on 2011-02-17 for aircraft engine attachment pylon comprising a box with a circular or elliptical shaped section.
This patent application is currently assigned to AIRBUS OPERATIONS(inc as a Societe par Act Simpl.). Invention is credited to Jacques Herve Marche, Fabien Raison.
Application Number | 20110036943 12/989589 |
Document ID | / |
Family ID | 39967306 |
Filed Date | 2011-02-17 |
United States Patent
Application |
20110036943 |
Kind Code |
A1 |
Marche; Jacques Herve ; et
al. |
February 17, 2011 |
AIRCRAFT ENGINE ATTACHMENT PYLON COMPRISING A BOX WITH A CIRCULAR
OR ELLIPTICAL SHAPED SECTION
Abstract
An engine attachment pylon for an aircraft, including a rigid
structure including a box formed by one or plural hollow segments.
The section of at least one hollow segment is circular or
elliptical in shape.
Inventors: |
Marche; Jacques Herve;
(Toulouse, FR) ; Raison; Fabien; (Plaisance Du
Touch, FR) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
AIRBUS OPERATIONS(inc as a Societe
par Act Simpl.)
Toulouse
FR
|
Family ID: |
39967306 |
Appl. No.: |
12/989589 |
Filed: |
May 12, 2009 |
PCT Filed: |
May 12, 2009 |
PCT NO: |
PCT/FR09/50861 |
371 Date: |
October 25, 2010 |
Current U.S.
Class: |
244/54 |
Current CPC
Class: |
B64D 27/26 20130101;
B64D 27/18 20130101; B64D 2027/264 20130101 |
Class at
Publication: |
244/54 |
International
Class: |
B64D 27/26 20060101
B64D027/26 |
Foreign Application Data
Date |
Code |
Application Number |
May 14, 2008 |
FR |
0853116 |
Claims
1-10. (canceled)
11. An engine attachment pylon for an aircraft, the pylon
comprising: a rigid structure including a box formed by one or
plural hollow segments, wherein a section of at least one hollow
segment is elliptical or circular in shape.
12. A pylon according to claim 11, wherein at least one hollow
segment is approximately in a shape of a tapered and truncated cone
or is approximately cylindrical, with the cross-section being
elliptical or circular in shape.
13. A pylon according to claim 11, comprising plural hollow
segments connected to each other at their forward and aft ends.
14. A pylon according to claim 13, wherein at least one hollow
segment has at least one of its forward and aft ends in a form of
an attachment flange projecting outwards from a space inside the
box.
15. A pylon according to claim 14, wherein two adjacent hollow
segments are assembled to each other through two facing attachment
flanges bearing on each other, and fixed by attachment means
outside the space inside the box.
16. A pylon according to claim 15, wherein the attachment means
includes bolts or rivets.
17. A pylon according to claim 11, further comprising a forward
hollow tapered and truncated segment with a circular cross-section,
and a central hollow segment supporting the forward segment, the
central hollow segment being approximately cylindrical in section
in a form of an ellipse with an inclined axis intersecting the axis
of the forward segment.
18. A pylon according to claim 11, wherein a box inner space forms
a duct through which compressed air can pass.
19. An engine assembly for an aircraft comprising: an engine; and
an attachment pylon for the engine, wherein the pylon is an
attachment pylon according to claim 11.
20. An aircraft comprising at least one engine assembly according
to claim 19.
Description
TECHNICAL FIELD
[0001] This invention relates in general to an engine attachment
pylon for an aircraft such as a turbojet. This type of attachment
pylon is also called an EMS (Engine Mounting Structure), and for
example can be used to suspend the turbojet below the aircraft
wing, using an assembly system comprising a plurality of engine
attachments.
STATE OF PRIOR ART
[0002] Such an attachment pylon is designed to form an attachment
interface between an engine such as a turbojet and the aircraft
wing. It transmits forces generated by its associated turbojet to
the structure of this aircraft, and it also enables routing of
fuel, electrical, hydraulic and air systems between the engine and
the aircraft.
[0003] In order to transmit forces, the pylon comprises a rigid
structure, also called the primary structure, frequently of the
"box" type, formed by the assembly of upper and lower spars and two
lateral panels, preferably through bolt type attachment means,
connecting them to transverse ribs located in an inner space within
the box. Therefore the cross-section through this box is normally
square or rectangular in shape.
[0004] The disadvantage of such a solution lies in the difficulty
of achieving a satisfactory compromise between making the box small
enough to limit the drag generated within the secondary flow in
which it is immersed, and large enough to transmit engine forces to
the aircraft fuselage.
SUMMARY OF THE INVENTION
[0005] Therefore, the purpose of the invention is to propose an
aircraft engine attachment pylon at least partially overcoming the
disadvantage mentioned above related to embodiments according to
prior art, and also to present an engine assembly for an aircraft
with at least one such pylon.
[0006] To achieve this, the object of the invention is an aircraft
engine attachment pylon, said pylon comprising a rigid structure
provided with a box formed by means of one or several hollow
segments. According to the invention, the section of at least one
hollow segment is elliptical or circular in shape.
[0007] Thus, the invention discloses a design that is radically
different from that usually used for rigid attachment pylon
structures, since it is rounded in shape, and more specifically it
has a circular or elliptical section. This shape was selected
because of the resulting compactness, and also for its very good
mechanical properties due in particular to the high modulus of
inertia in the three principal directions orthogonal to each other,
these three principal directions corresponding to the main loading
modes that are vertical bending, lateral bending and torsion.
Consequently, this innovative solution advantageously offers a
satisfactory compromise between the box being small enough to limit
the drag generated by the secondary flow in which this box is
immersed, and large enough to transmit engine forces to the
aircraft fuselage.
[0008] Preferably, at least one hollow segment is approximately in
the shape of a tapered and truncated cone or is approximately
cylindrical, with the cross-section being elliptical or circular in
shape. Naturally, this type of segment could be combined with
another segment of any arbitrary shape.
[0009] Preferably, the pylon comprises several hollow segments
connected to each other at their forward and aft ends.
[0010] In this case, at least one hollow segment has at least one
of its forward and aft ends in the form of an attachment flange
projecting outwards from a space inside the box. Obviously, this
flange is preferably intended to be connected to a similar flange
placed facing it on the adjacent segment of the box.
[0011] Preferably, two adjacent hollow segments are assembled to
each other through their two facing attachment flanges bearing on
each other, and fixed by attachment means outside said space inside
the box.
[0012] This solution also differs from solutions according to prior
art with a rectangular or square cross-section in which several
accesses to the inside of the box are usually provided to install
and assemble the attachment means for the components of this box.
For example, these accesses may be in the form of "doors" or
"openings" formed on the spars and the panels. Nevertheless,
regardless of the adopted design, access for the operator is always
difficult, which increases assembly and manufacturing times.
[0013] On the other hand, the adopted pylon design no longer
requires any access inside the box to put said attachment means
into place, since the portions to be assembled are located outside
the space inside the box. Consequently, the assembly time is
advantageously shortened, particular because the work to be done by
the operator performing the task is made easier.
[0014] Note that the box is preferably provided without any
internal ribs, even if such ribs may be provided without going
outside the framework of the invention. However, forward and aft
box closing ribs can be used conventionally, located on the
opposite longitudinal ends of this box and therefore remaining
easily accessible for the operator who will fix them.
[0015] Preferably, said attachment means are bolts or rivets.
[0016] Also preferably, the pylon comprises a hollow forward
tapered and truncated segment with a circular cross-section, and a
central hollow segment supporting said forward segment, the central
hollow segment being approximately cylindrical in section in the
form of an ellipse with an inclined axis intersecting the axis of
said forward segment. This configuration facilitates the junction
between the two segments. It also makes it possible to use an
elliptical cross-section for the main segment and therefore to
orient the major axis of the ellipse along the direction of maximum
load applied to the box, which is usually in the direction of the
height.
[0017] Finally, said inner space may be in the form of a duct
through which compressed air can pass, preferably drawn off from
the engine, and that will supply the inside of the aircraft, for
example to satisfy aircraft pressurisation needs. Alternatively, a
compressed air duct could be routed through the inner space in the
box.
[0018] Another purpose of the invention is an engine assembly for
an aircraft with an engine and an engine attachment pylon like that
described above. Finally, another purpose of the invention is an
aircraft comprising at least one such engine assembly.
[0019] Other advantages and characteristics of the invention will
become clear after reading the detailed non-limitative description
given below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] This description will be made with reference to the appended
drawings wherein;
[0021] FIG. 1 shows a diagrammatic side view of an aircraft engine
assembly, according to one preferred embodiment of this
invention;
[0022] FIG. 2 shows a perspective view of the rigid structure of
the engine assembly attachment pylon shown in FIG. 1;
[0023] FIG. 3 shows a longitudinal sectional view of the rigid
structure of the attachment pylon shown in FIG. 2;
[0024] FIGS. 4a to 4c are sectional views taken along lines IVa-IVa
to IVc-IVc in FIG. 3 respectively;
[0025] FIG. 5 shows a view similar to that shown in FIG. 3, in
which the rigid structure is in the form of another preferred
embodiment of this invention; and
[0026] FIGS. 6a to 6c are sectional views taken along lines VIa-VIa
to VIc-VIc in FIG. 5 respectively;
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0027] FIG. 1 shows an engine assembly 1 for an aircraft designed
to be fixed under a wing 3 of this aircraft, this assembly 1
provided with an attachment pylon 4 being in the form of a
preferred embodiment of this invention.
[0028] Globally, the engine assembly 1 comprises an engine such as
a turbojet 2 and the attachment pylon 4, the attachment pylon in
particular being provided with a rigid structure 10 and an assembly
system 11 comprising a plurality of engine attachments 6, 8 and a
device for resistance of thrusts 9 generated by the turbojet 2,
therefore the assembly system 11 being inserted between the engine
and the above-mentioned rigid structure 10 also called the primary
structure. Note that the assembly 1 is intended to be surrounded by
a pod (not shown) and that the attachment pylon 4 comprises another
series of attachments 13 used to suspend this assembly 1 under the
aircraft wing, being connected to a forward spar (not shown) of
this wing.
[0029] By convention, throughout the following description, the X
direction denotes the longitudinal direction of the pylon 4 that
can also be considered to be the longitudinal direction of the
turbojet 2, this X direction being parallel to a longitudinal axis
5 of this turbojet 2. Furthermore, the direction transverse to the
pylon 4 is denoted Y and can be considered to be the same as the
transverse direction of the turbojet 2, and Z is the vertical
direction or the height, these three X, Y and Z directions being
orthogonal to each other.
[0030] Furthermore, the terms "forward" and "aft" should be
considered with respect to a direction of movement of the aircraft
that occurs as a result of the thrust applied by the turbojet 2,
this direction being shown diagrammatically by the arrow 7.
[0031] In FIG. 1, it can be seen that only the thrust resistance
device 9, engine attachments 6, 8 and the rigid structure 10 of the
attachment pylon 4 are shown. The other components of this pylon 4,
such as the attachment means of the rigid structure 10 under the
aircraft wing, or the secondary structure for segregation and
maintenance of systems while supporting aerodynamic fairings, are
not shown.
[0032] The turbojet 2 is provided with a large fan casing 12 at the
forward end delimiting an annular fan duct 14, and being provided
near the aft end with a smaller central casing 16 enclosing the
core of this turbojet. Finally, the central casing 16 is prolonged
in the aft end by an ejection casing 17 that is larger than the
casing 16. Obviously, the casings 12, 16 and 17 are rigidly fixed
to each other.
[0033] As can be seen in FIG. 1, the plurality of engine
attachments is composed of a forward engine attachment 6 and an aft
engine attachment 8 possibly forming two aft half-attachments as
known in prior art. The thrust resistance device 9 comprises in
particular two lateral thrust resistance rods (only one of which is
shown in FIG. 1 because the figure shows a side view) connected
firstly to a forward part of the central casing 16 at their forward
ends, and secondly to a spreader beam 20 at their aft ends, this
spreader beam itself being mounted on the rigid structure 10 or on
an aft attachment body as shown.
[0034] The forward engine attachment 6, fixed to the fan casing 12,
is conventionally designed so that it can resist only forces
generated by the turbojet 2 along the Y and Z directions, and
therefore not forces applied along the X direction. Note that this
forward attachment 6 preferably penetrates into an upper
circumferential end piece of the fan casing 12.
[0035] The aft engine attachment 8 is globally inserted between the
ejecting casing 17 and the rigid structure 10 of the pylon. As
mentioned above, it is preferably designed so as to be able to
resist forces generated by the turbojet 2 along the Y and Z
directions, but not forces applied along the X direction.
[0036] Thus, with the statically determinate assembly system 11,
forces applied along the X direction are resisted by the device 9,
and forces applied along the Y and Z directions are resisted by the
forward attachment 6 and the aft attachment 8 acting in
combination.
[0037] Also, the moment applied about the X direction is resisted
vertically by means of the attachment 8, the moment applied about
the Y direction is resisted vertically by means of the aft
attachment 8 jointly with attachment 6, and the moment applied
about the Z direction is resisted transversely by means of the
attachment 8, jointly with the attachment 6.
[0038] FIGS. 2 to 4c show the design of the rigid structure 10 of
the attachment pylon, also referred to as the primary structure.
Globally, it is composed of a box 24 extending over the entire
length of the rigid structure 10 along the X direction, and
therefore forms a torsion box.
[0039] The box is composed of several hollow segments, in this case
three adjacent segments 28, 30, 32. The first of these segments is
tapered and truncated, with its axis 28a corresponding to the axis
of revolution. Its forward end is preferably designed to support
the forward engine attachment 6. The section orthogonal to the axis
28a is in the shape of a circle as shown in FIG. 4a. Thus, the size
of this circle reduces towards the forward end due to the reduction
in size of the tapered and truncated segment along this
direction.
[0040] The second hollow segment 30 called the central segment is
approximately cylindrical with its axis 30a preferably being
coincident with the axis 28a. Its forward end, fixed to the aft end
of the first segment 28, is preferably designed to support the aft
engine attachment 8. The section orthogonal to the axis 30a is in
the shape of a circle as shown in FIG. 4b. Preferably, to
facilitate assembly of segments 28 and 30 to each other, the
diameter close to the forward end of the second segment 30 is very
similar to the design of the first segment 28 close to its aft
end.
[0041] Finally, the third segment is tapered and truncated, with
its axis 32a corresponding to the axes 28a and 30a and therefore
also corresponding to the axis of revolution. The section
orthogonal to the axis 32a is in the shape of a circle as shown in
FIG. 4c. Thus, the size of this circle reduces towards the aft end
due to the reduction in size of the tapered section along this
direction, which is perfectly adapted to the narrowing of the pylon
is this aft part. Preferably, to facilitate assembly of segments 30
and 32 to each other, the diameter close to the aft end of the
second segment 30 is very similar to the design of the third
segment 32 close to its forward end.
[0042] Note that although the coaxial segments have been described
as having a constant or varying circular cross-section, an
elliptical cross-section would also be possible without going
outside the scope of this invention, even for significantly tapered
sections. Similarly, the segments are not necessarily coaxial,
although they preferably have intersecting axes depending on the
needs encountered.
[0043] Each segment may be made from a composite material, for
example using the composite winding technique, or even by Resin
Transfer Molding.
[0044] The outer surface of the box 24 is also used as a housing
for the installation of normal systems such as hydraulic and/or
electrical systems on the pylon.
[0045] As shown diagrammatically in FIG. 3, the box forming the
rigid structure 10 may also comprise a forward transverse box
closing rib 34a, and an aft transverse box closing rib 34b.
[0046] The forward and/or aft ends of each of the segments 28, 30,
32 will be in the form of an attachment flange projecting outwards
from a space inside the box 38, so each of these segments can be
connected to the next segment. Therefore, these coaxial circular
flanges 40 centred on the segment axes preferably bear in contact
with the adjacent flange and project radially outwards from the
segments. FIGS. 2 and 3 show that the aft flanged end 40 of the
forward segment 28 is fixed to the flanged forward end 40 of the
central segment 30, and similarly the aft flanged end 40 of the
central segment 30 is fixed to the flanged forward end 40 of the
aft segment 32. The attachment means used to make such assemblies
are bolts 42, or rivets or similar means, placed outside the box
38, and are preferably oriented along the X direction.
[0047] According to one preferred embodiment shown in FIGS. 5 to
6c, the rigid structure 10 of the attachment pylon is also globally
composed of a box 24 extending over the entire length of the rigid
structure 10 along the X direction, and therefore forming a torsion
box. This box is composed of several hollow segments, in this case
three adjacent segments 28, 30, 32. The first of these segments is
tapered and truncated, with its axis 28a corresponding to the axis
of revolution. Its forward end is preferably designed to support
the forward engine attachment 6. The section orthogonal to the axis
28a is in the shape of a circle as shown in FIG. 6a. Thus, the size
of this circle reduces towards the forward end due to the reduction
in size of the tapered segment along this direction.
[0048] The second hollow segment 30 called the central segment is
approximately cylindrical with its axis 30a inclined to and
intersecting the axis 28a. More precisely, the axis 30a of the
central segment is approximately parallel to the X direction, the
axis 28a being inclined relative to it so that the distance between
it and the engine axis 5 becomes smaller further forwards. In any
case, the two intersecting axes 28a, 30a are preferably located in
an imaginary vertical XZ median plane of the pylon.
[0049] The forward end of this central segment, fixed to the aft
end of the first segment 28, is preferably designed to support the
aft engine attachment 8. The section orthogonal to the axis 30a is
in the shape of an ellipse as shown in FIG. 6b. Therefore, the
major axis of this ellipse lies along the vertical direction and
the modulus of inertia of the segment in this direction is very
large. Advantageously, the vertical direction is the direction in
which the mechanical loads applied to the pylon to resist engine
forces are greatest.
[0050] Preferably, the aft end of the segment 28 is located in a
plane 50 inclined relative to the plane 52 orthogonal to the axis
28a to facilitate assembly of segments 28 and 30 to each other, and
to have an ellipse shape very similar to the ellipse shape of the
second segment 30. Preferably, the plane 50 concerned is almost
orthogonal to the axis 30a of the main segment 30, and also
corresponds to the plane in which the forward end of the main
segment 30 is located.
[0051] Finally, the third segment 32 is significantly tapered and
truncated, with its axis 32a corresponding to the axis 30a and also
forming an axis of revolution. The section orthogonal to the axis
32a is in the shape of an ellipse as shown in FIG. 6c. Thus, the
size of this ellipse reduces towards the aft end due to the
reduction in size of the tapered section along this direction,
which is perfectly adapted to the narrowing of the pylon is this
aft part. Once again, to facilitate assembly of segments 30 and 32
to each other, the elliptical section of the second segment 30 is
very similar to the section of the third segment 32 close to its
forward end.
[0052] Obviously, the segments are connected to each other by
attachment means 42 described above passing through the flanges 40
bearing on and being in contact with each other and arranged
outside the space 38.
[0053] Furthermore, regardless of the envisaged embodiment, this
inner space 38 forms a duct through which compressed air drawn off
from the engine can pass as an air supply to the aircraft.
[0054] Obviously, those skilled in the art could make various
modifications to the assembly 1 and to the aircraft attachment
pylon 4 that have just been described, solely as non-limitative
examples. In this respect, it is worth mentioning that although the
pylon 4 has been presented in an adapted configuration for it to be
suspended under the aircraft wing, this pylon 4 could also be
presented in a different configuration so that it could be mounted
above this wing, and possibly even in the aft part of the aircraft
fuselage.
* * * * *